Friction draft gear



March 24, 1931. G F. CQUCH FRICTION DRAFT GEAR Filed Jan. 19, 1926Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE GLENN IE. COUCH, OFROCHESTER, NEW YORK, ASSIGNOR T'O THE'GOULD'COUPLER COMPANY, OF NEWYORK, N. Y., A CORPORATION OF MARYLAND FRICTION DRAFT GEAR Applicationfiled January 19, 1926. Serial No. 82,364.

This invention relates to draft gear and, more particularly, to acombined spring and friction n'lechanism in which the frictionalresistance is generated by a rotary motion between component members ofthe gear, said mechanism being particularly suitable as cushioningmechanism in railway car draft rigging.

The principal object of the invention, generally considered, is theprovisionof a compact and economically constructed cushioning unit forrailway draft rigging in which a rotary element or plunger is threadablymounted in a casing or housing whereby, when the gear is compressed,frictionis generated at the threaded engagement between the parts, saidfrictional resistance being preferably supplemented by springresistance.

An object of my invention is the provision of a draft gear inwhich apair of followers are mounted for axial movement in the opposite ends ofa housing, said housing being threaded to an internal plunger adapted tomove axially and rotatably with respect thereto, one end of said plungerbeing preferably frictionally engaged by one follower and the other endreceiving a spring resiliently engaging the other follower whereby, whenthe gear is compressed, the plunger generates frictional resistance withrespect to the housing and one follower and spring resistance isprovided between the plunger and the other follower.

Another object of my invention is the provision of a cushioningmechanism for railway draft gear involving a follower with a conicalrecess in one surface thereof, aplunger formed with a correspondingconical end engaged in said recess and threadably mounted in acooperating housing and spring pressed against the follower whereby,when the gear is compressed, the plunger is rotated with respect to thefollower and frictional resistance generated therebetween, saidfrictional resistance being preferably supplemented by springresistance.

A further object of my invention is the provision of a draft gearcomprising a housing in which is threadably mounted a plunger and onopposite sides of said plunger are mounted followers, said followersbeing arranged for only axial motion with respect to said housing andone of said followers frictionally engaged by the plunger and the otherresiliently engaged by a spring extending from the plunger, said springbeing so fastened to the plunger and engaging follower upon its oppositeends that, upon compression of the gear, said spring is stressedtorsionally.

Other objects and advantages of the in-' vent-ion relating to theparticular arrangement and combinationof the various parts will becomeapparent as the description proceeds. i

Referring to the'drawings illustrating my invention, the scope whereofis defined by the appended claims:

Figure 1 is a plan View, partially in section, of a railway draftrigging mounted on a car underframe.v and embodying my invention.

Figure 2 is ahorizontal central section of the draft gear or cushioningmechanism em-. bodying my invention.

Figure 3 is an end elevation of the draft gear or cushioning mechanismillustrated in Figure 2. '7

Referring to the drawings in detail, like 'parts being designated bylike reference characters, the draft of center sills l of a railway carare illustrated in Figure 1 and on the inner surfaces of the webs ofsaid sills are fastened the usual draft lugs 2, said draft lugs engaginga follower 3 and rear follower l, said rear follower 4 forming a cap orcover over the rear end of the gear or cushioning mechanism casing 5.Around the draft gear or cushioning mechanism a yoke 6 extends, saidyoke, in the present instance, being illustrated as of the vertical typeand supported at its rear and intermediate portions by carrier irons 7.Said carrier irons 7 are preferably connected to the lower flanges ofthe draft sills 1 by means of bolts or the like, as illustrated;

The forward portion of the yoke 6 is connected with the stem of thecoupler 8, in the present embodiment, by means of a horizontal draft key9, said draft key extending through corresponding slots in the coupler,yoke and through registering slots 10 in the center sills and similarslots 11 in the associated draft lugs 2.

The follower 3, which engages the front draft lugs 2 at its forwardsurface, engages at its rear, 01' is formed as a part of, the frontfollower 12 of the gear or cushioning mechanism proper.

cal surface 13 which is frictionally engaged by a complementary andsimilarly formed conical surface 14 on a plunger or friction element 15which is threaded into the body of the housing or casing 5. Said plunger15 is preferably formed generally hollow so that the opposite end fromthe friction surface 14 is formed with a recess or cup-shaped portion 16in which is preferably received a coil spring 17. The coil spring 17 ispreferably, but not necessarily, formed of material square orrectangular in section, as illustrated. One end of said coil springengages the bottom of the recess 16 in the plunger 15and the other endengages the adjacent face of an intermediate follower 18. Positionedbetween the intermediate follower 18 and the rear follower & is springmeans which preferably takes the form of a pair of coil or helicalsprings 19 and 20, said springs preferably nesting one within the otherand being oppositely wound to avoid interference between the coilsthereof. For holding all the parts of the gear or cushioning mechanismproper in assembled relation under a predetermined initial tension, abolt or longitudinal retaining means 21 is preferably inserted throughalined axial apertures in the end followers, intermediate follower andplunger, the head of the. bolt, as well as the nut on the opposite endthereof, being preferably countersunk beneath the end surfaces of thefront and rear followers to avoid interference between the same and theengagingmei-nbers of the draft rigging, as illustrated particularly inFigure 2, said construction also permitting compression of the gear tothe normal extent either by 'countersinking to a corresponding extent orby forming the cooperating follower 3' with a corresponding aperture.

The threaded engagement between the plunger 15 and the housing 5 ispreferably ef fected by forming internal threads '22 on the housing,said threads being preferably of relatively great pitch and formed withfriction surfaces 23 preferably arranged substantially transverse withtheir axial sections substantially normal or vertical with respect tothe axis ofthe gear, as illustrated in Figure 2. The other portions of"the threads 22 may be defined by sloping substantially conical orhelical planes21 joined with the transverse or normal surfaces 23 at thecrowns and bases of the threads 22 by cylindrical surfaces '25 and 26,respectively. The threads '22 ap- The inner face of the "front Ifollower 12 is preferably formed with a com ing, there are formedsubstantially normal or transverse friction surfaces on the threads ofthe housing and plunger and sloping oppositely-disposed surfaces whichgenerally engage only when the gear is released, the main frictionsurfaces normally engaging when the gear is compressed. v

It will be apparent that, on account of the threaded engagement betwenthe housing 5 and plunger 15, when the gear is compressed,

the follower 12 moves axially with respect to said housing 5 and theplunger 15 moves axially therewith to the-same extent but is rotated, atthe same time, due to its threaded engagement in the housing. Therelative rotation between these members depends upon the pitch of thethreads, as will be understood, the greater the pitch, the less therelative rotation between theparts. It will be obvious, however, that,in order to effect a closure or compression of the gear, the pitchcannot be smaller than a given ratio which would depend on the angle offriction between the plunger and housing. Between this limiting pitchand a greater pitch, the capacity of the gear may be varied-to agreatdegree in accordance with the varying pitch of the threads, 7

In order to utilize the strength of the spring 17 torsionally as well ascompression ally, a lug-27 is preferably formed on the bottom of therecess 16 of the plunger 15 and engaged by the corresponding end of thespring 17. A complementary lug 28 is formed on the intermediate follower18 engaged by the corresponding end of the spring 17. In order toprevent the intermediate follower 18 from turning with respect to thehousing 5, the same is preformed noncircular in cross section orprovided with an extension or extensions 29 fitting into a correspondinggroove or grooves 30 in thehousing 5. This construction permits axialmovement of the intermediate follower 29- with respect to the housing 5but preventsrot'ary or turning movement therebetween. On account of thisconstruction, when the gear is compressed, the plunger 15 is rotated aswell as moved axially withrespect to the housing 5 thereby compressingthe spring 17 as well as twisting or stressing the same torsiona llybecause of the holding lugs 27 and 28 engaging the corresponding ends-ofsaid spring.

In order to prevent the follower 12 from rotating with respect to thehousing, insteadof being held for rotary movement of the p'lunger'15with respeot thereto,'said follower is formed in a manner similar to thefollower 18, that is, it is non-circular in cross section or providedwith a lug or lugs 31 fittinginto a corresponding recess or recesses 32in the easing thereby permitting only axial motion between the parts.For uniformity, the rear follower or cap 4 preferably cooperates in asimilar manner with respect to the corresponding end of the housing 5,that is, it may be formed of a contour correspondingwith that of thehousing 5 so that only axial motion between the parts is permitted, aswill be understood.

In assembling the gear, the plunger is preferably first positioned withrespect to the housing 5 substantially as shown in Figure 2, the spring17 placed in position with the end thereof engaging the lug 27 and thefollower 29 slipped in place so that the lug 28 thereon engages theother end of the spring 17. The springs 19 and 20 and the end followersmay then be applied, the bolt 21 inserted in place and the nut thereontightened to place the gear under the desired initial compression.

\Vhen the gear is compressed, for example, when associated with draftrigging, as shown in Figure 1, either upon buffing or draft forces beingapplied to the coupler, a compression will first probably be effected ofthe springs 19 and 20 until sufficient force is applied to overcome thefriction between the conical surfaces 13 and 14 and the frictionsurfaces on the threads 22 and 22*. hen the gear is further compressed,the end followers move 9;; inwardly, the plunger 15 moves inwardly withthe front follower 12 and, at the same time, rotates with respect to thehousing 5 generating frictional resistance where it is threaded intosaid housing as well as at tho conical engaging surfaces 13 and 1 1.This rotary movement between the plunger 15 and the housing 5 causes, inaddition to the compression of the spring 17, a torsion or twisting ofsaid spring due to the engagement of the lugs 27 and 28 with thecorresponding ends thereof.

In view of the foregoing, it will be apparent that I have devised adesirable draft gear or cushioning mechanism especially adapted forrailway, draft rigging in which resistance to compression of the gear isdeveloped, not only by spring means, but also by the frictionalengagement between the rotating threaded plunger 15 and the associatedhousing and front follower. In addispring with the adjacent surfaces forthe transmission of tensile rather than merely compressive stress. Inaddition to the forces mentioned, a slight amount of frictionalresistanceis also generated by the movement 1. In a draft gear, a pairof followers, an

internally threaded member receiving both followers, a correspondinglyexternally threaded member cooperating with the first threaded memberand engaged by one of the followers, resilient means between said memherand the other follower, and opposing resilient means to hold saidfollower in place.

2. In a draftwgear, .a pair of followers, a

housing extending the entire distance be-- tween said followers, aplunger frictionally engaging one follower and threaded into thehousing, and a coil spring extending between the plunger and the otherfollower and engaging lugs on the respective members whereby, when theplunger is rotated with respect to the second follower, the spring isplaced under torsional stress.

3. In a draft gear, a pair of followers, a hollow housing provided withopposite recesses into which said followers fit, a hollow I plungerfitting in said housing and threaded thereto, one end of said plungerbeing closed by a wall frictionally engaging one follower and the openend of the plunger containing a coil spring acting on the other followerand being stressed when the gear is compressed.

l. In a draft gear, a pair of followers, an

internally threaded member engaged by one follower, a member threadedinto said internally threaded member and cooperating with the other ofsaid followers, resilient means between said member and the firstfollower and resilient means between said first follower and anotherfollower for receiving the initial load 011 the gear. 7

5. In a draft gear, a pair of end followers and an intermediatefollower, a housing slidably engaged by said end followers and slid ablyinclosing the intermediate follower, coil spring means extending betweenthe intermediate and an end follower and frictional spring meansextending between the other end follower and the intermediate follower,said means comprising a plunger threaded into said housing andfrictionally engaging the end follower, and a coil spring received insaid plunger and resiliently engaging the intermediate follower.

6. In a draftgear, an end follower formed with a conical recess, aplunger formed with a complementary conical end fitting in said,

recess and provided with relatively large threads arranged at arelatively great pitch on the exterior surface thereof, a housingsurrounding said plunger and in which the follower fits, said housingbeing formed with internal threads complementary to and engaging theexternal threads on the plunger for receiving frictionalresistancetherebetween, the other end of said housing containing an intermediatefollower, a spring positioned between said follower and the plunger,another en-d follower fitting the other end of the housing, and springmeans extending between said follower and the intermediate follower.

7Q In a draft gear, a pair of end followers, a housing fitting betweensaid followers, a plunger frictionally engaging one of said endfollowers and threadably engaging the housing, an intermediate followercontained in said housing and arranged for only longitudinal motion withrespect thereto, a coil spring fitting in a recess in the plunger andengaging the intermediate follower, said intermediate follower andplunger being provided with lugs adjacent the ends of the springwhereby, when the gear is compressed and the plunger rotated withrespect to the second follower, the spring is placed under torsionalstress, and resilient means extending between said intermediate followerand the other end follower.

8. In a draft gear, a pair of end followers, a hollow housing, the endsof which slidably engage said followers, an intermediate followerpositioned between said end followers and contained in said housing, ahollow plunger fitting in said housing and threaded thereto, one end ofsaid plunger being formed as a'cone frictionally engaging acomplementary surface on the adjacent end follower and the other end ofthe plunger containing a coil spring acting on the intermediate followerfor being stressed when the gear is placed in compression, spring meansextending between the intermediate follower and the other end follower,and-a retaining bolt extending through central perforations in thefollowers and plunger for holding the gear in assembled relation. 7

In testimony whereof I alfix my signature.

GLENN F. COUCH. V

